Lennox CHA16 - A4 diagram with B2 diagram ECH16-82;95;135;160 50 kW 208;230 V Operating Sequence; Operation Sequence: A4 Section and B2 Sections (50 kW 208;230 V electric heat wired to CHA16-1603); 1- Control voltage in this heater is supplied by a separate transformer T2...; 2- 1 st stage heating demand closes W1...

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A4 diagram
with B2 diagram
ECH16-82/95/135/160 50kW 208/230V Operating Sequence
Operation Sequence: A4 Section and B2 Sections
(50kW 208/230V electric heat wired to CHA16-1603)
1- Control voltage in this heater is supplied by a separate transformer T2 which is powered at all
times.
2- 1st stage heating demand closes W1. W1 energizes relay K9.
3- When K91 switches, indoor blower contactor K3 is energized. The indoor blower is pow
ered (and optional economizer opens to minimum position when K32 contacts close).
When K92 closes, second stage heat is enabled. When K93 closes, control voltage
passes through primary limit S15 to energize contactor K15 and time delay DL2.
4- When K151 closes, heating elements HE1 are energized. All elements are arranged in a Del
ta" configuration for 208/230V operation.
5- DL2 closes 30 seconds later to energize contactor K16.
6- When K161 closes heating elements HE2 are energized.
7- Additional heating demand W2 passes through K92 to energize relay K19.
8- When K191 switches, time delay DL4 is energized. DL4 closes 30 seconds later to energize
contactor K17 and time delay DL5.
9- When K171 closes heating elements HE3 are energized,
10- DL5 closes after 30 seconds to energize contactor K18 is energized.
11- When K181 closes, heating elements HE4 are energized.